1. Field of the Invention
The present invention relates to an equipment for manufacturing a printed circuit board including a base member and a multilayer wiring pattern arranged in the base member.
2. Description of the Related Art
In a conventional manufacturing method of a printed circuit board, a plurality of resin films made of a thermoplastic resin is stacked and is pressed and heated so as to formed a base member including a multilayer wiring pattern as described, for example, in US 2003/0209796 A (corresponding to JP-A-2003-86948).
In the above-described method, a conductive pattern is formed on a single side of each of the resin films. The resin films are stacked in a stacking direction to configurate a laminated body. The resin films are treated with a hot pressing. That is, the resin films are pressed and heated from above and below in the stacking direction. Thereby, the resin films adhere to each other and a printed circuit board is formed.
If the laminated body is pressed and heated directly by hot-pressing plates, a pressure applied to each portion of the laminated body may vary due to inclination and undulation of the hot-pressing plates, and unevenness of the laminated body. The unevenness of the laminated body is caused by a variation in density of the conductive patterns and connectors for connecting the conductive patterns arranged on different layers. The variation in the pressure may cause pattern flowing, poor interlayer connection, and insufficient interlayer adhesion.
In a first example of the related art illustrated in FIG. 9, a buffer member 280 is disposed between a hot-pressing plate 221 and a laminated body 290. The laminated body 290 is pressed and heated by the hot-pressing plate 221 and a hot-pressing plate 220. The buffer member 280 has a low elastic modulus so as to be deformable and has a high heat resistance so as to withstand heat during the hot pressing. For example, the buffer member 280 has a compressive elastic modulus less than or equal to about 10 MPa. In such a case, variation in a pressure applied from the hot-pressing plates 220 and 221 to each portion of the laminated body 290 can be reduced.
However, the buffer member 280 having a low elastic modulus may act like fluid. Thus, during the hot pressing, the buffer member 280 may be plastically deformed in a horizontal direction approximately perpendicular to the stacking direction as illustrated in FIG. 9. If the buffer member 280 is plastically deformed, a crack may generate in the buffer member 280. In such a case, a shape of the buffer member 280 does not recover after the hot pressing. Thus, the number of reusing the buffer member 280 may be reduced.
In a second example of the related art illustrated in FIG. 10, an upper pressing part 250 is further provided. The upper pressing part 250 has a base section 251 and a sidewall section 252. The base section 251 has a plate shape and transmits the heat and the pressure from the hot-pressing plate 221 to the laminated body 290 through the buffer member 280. The sidewall section 252 protrudes from the base section 251 so as to surround the whole area of a side surface of the buffer member 280. In such a case, the sidewall section 252 of the upper pressing part 250 can restrict flow of the buffer member 280 in the horizontal direction. If an end surface of the sidewall section 252 comes in contact with the hot-pressing plate 220, more pressure cannot be applied to the laminated body 90. Thus, the end surface of the sidewall section 252 is apart from the hot-pressing plate 220. Therefore, as illustrated in FIG. 10, the buffer member 280 may flow from a clearance between the upper pressing part 250 and the hot-pressing plate 220. In such a case, a deforming amount of the buffer member 280 may increase and the buffer member 280 may be plastically deformed. Thus, the number of reusing the buffer member 280 may be reduced.